A new multi-scale approach to characterize concrete creep and its implications in long-term durability

一种新的多尺度方法来表征混凝土徐变及其对长期耐久性的影响

基本信息

批准号：
RGPIN-2016-06077
负责人：
Sorelli, Luca
金额：
$ 1.75万
依托单位：
Université Laval
依托单位国家：
加拿大
项目类别：
Discovery Grants Program - Individual
财政年份：
2019
资助国家：
加拿大
起止时间：
2019-01-01 至 2020-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=679512
关键词：
new multi scale approach characterize

项目摘要

A recent survey on 71 concrete bridges monitored over a period of about 20 years showed that the creep deflection increases incessantly and it overestimates by far the predictions of several national codes. A wake-up call was then launched stating that the current national design recommendations and codes “are not only theoretically obsolete, but also indefensible”. The proposed research program aims at better understanding and characterizing the long term creep of concrete, and finally, to enhance the current design methods for predicting the long term behavior. ***Estimating the long-term creep of concrete (e.g., 30-50 years) using short term creep tests (e.g., 3-12 months) has been an unavoidable crux in civil engineering. In this context, novel microindentation techniques have been provided a breakthrough solution as they allow characterizing the logarithmic nature of the long term creep in few minutes. From a design point of view, the modern model code fib 2010 has recently adopted a logarithmic function for predicting the long term creep. This is extremely appealing for the proposed research program which intends to develop micro-indentation techniques to rapidly estimate the parameters of such logarithmic function for predicting the long term creep of concrete. ***The specific objectives of this research program are: ***(1) At the microstructure level, to fully characterize and better understand the effect of the temperature and possible damage on the creep behaviour of a cement paste by means of microindentation tests; ***(2) Upscale the properties measured at the level of a cement paste to the concrete level; ***(3) To implement a numerical model for predicting the long term deformation of a structure at different environmental conditions (e.g., temperature) and with possible damage due to durability issues;***(4) To improve the current design methods on the prediction of the long term creep; ***(5) To develop an international network of excellence and train students in highly specialized competences.***This innovative research direction will provide outstanding contributions to civil engineering, such as: ***(i) Fostering the current understanding on the long term creep of concrete with emphasis on its dependence on temperature and damage; ***(ii) Developing of ultra-rapid microindentation techniques for characterizing the long term creep of cement paste; ***(iii) Developing engineering tools for better predicting the long term creep of a concrete structures, such as bridges; ***(iv) Contribution to enhanced design recommendations for better predicting the long term creep of concrete structures and assuring the desired durability of the future Canadian infrastructure. *****

最近对 71 座混凝土桥梁进行了约 20 年监测的调查显示，蠕变挠度不断增加，远远高估了多个国家规范的预测，这敲响了警钟，指出当前的国家设计建议和标准。所提出的研究计划旨在更好地理解和表征混凝土的长期徐变，并最终增强当前预测长期行为的设计方法。 ***使用短期蠕变试验（例如 3-12 个月）来估计混凝土的长期蠕变（例如 30-50 年）一直是土木工程中不可避免的关键问题。在此背景下，新型微压痕技术已成为现实。提供了突破性的解决方案，因为它们可以在几分钟内表征长期蠕变的对数性质，从设计的角度来看，现代模型代码 fib 2010 最近采用了一种方法。用于预测长期蠕变的对数函数对于拟开发微压痕技术以快速估计用于预测混凝土长期蠕变的对数函数的参数来说非常有吸引力***具体目标。该研究计划的内容是： ***(1) 在微观结构层面，通过微压痕测试充分表征和更好地了解温度和可能的损害对水泥浆体蠕变行为的影响；***(2) ）升级所测量的属性从水泥浆水平到混凝土水平；***(3) 建立一个数值模型，用于预测结构在不同环境条件（例如温度）下的长期变形以及由于耐久性问题可能造成的损坏； ***(4) 改进当前长期蠕变预测的设计方法；***(5) 发展国际卓越网络并培养学生的高度专业能力。***这一创新研究方向将对土木工程做出杰出贡献，例如： ***(i) 培育目前对混凝土长期蠕变的理解，重点是其对温度和损伤的依赖性；***(ii) 开发用于表征水泥浆体长期蠕变的超快速微压痕技术；***(iii) 开发用于表征水泥浆体长期蠕变的技术；用于更好地预测混凝土结构（例如桥梁）的长期蠕变的工程工具；***(iv) 为增强设计建议做出贡献，以更好地预测混凝土结构的长期蠕变并确保未来加拿大基础设施的预期耐久性。 *****